GB2395795A

GB2395795A - Tension monitor

Info

Publication number: GB2395795A
Application number: GB0227714A
Authority: GB
Inventors: Christopher Andre Philip Lea
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-28
Filing date: 2002-11-28
Publication date: 2004-06-02
Anticipated expiration: 2022-11-28
Also published as: GB2395795B; GB0227714D0

Abstract

A tension monitor for fastener, support or tensioning systems comprising of a body 1 that incorporates a circular pressurised air chamber, an O ring seal 3 and a top 2 which when pressed against the O ring, due to the tension applied, makes the tension monitor air tight. The tension monitor has a central bore through which the fastener, support or tensioning system passes. Air is supplied to the tension monitor under pressure from a reservoir or other suitable source and the air pressure in the tension monitor detected by a pressure switch or some other pressure sensitive device. If the fastener, support or tensioning system fails or works loose the O ring 3 will lift off its seat and air will be lost from the tension monitor. This loss of air will be detected by the pressure switch or other air pressure sensitive device and will instigate a suitable warning indication and/or shut down the system being protected. The tension monitor is a fail- safe device as spurious leakage of air from it would activate one of the possible systems described.

Description

TENSION MONITOR

This invention relates to a tension monitor.

The failure of various components such as fixing screws, bolts, cables, chains, can in some applications have catastrophic/serious implications such as equipment detachment or collapse. In the case of vehicles (road, rail, aircraft) equipment detachment would result in very serious safety hazards.

The present invention comprises of a device that will monitor the tension in any type of fastener, support or tensioning system and it will provide a warning if the fastener, support or tensioning system works loose or fails completely. The warning could be in the form of either a visual or audible indicator or could provide automatic shutdown of the system as appropriate. The invention, using pneumatics, would be suitable for use in high voltage applications. It would also be safe to use in explosive atmosphere applications such as in mines, chemical plant or other industries where there is a risk of fire or explosion.

Preferably the top and body of the tension monitor is made of metal or plastics material or from a combination of these materials. The O ring would be a proprietary manufactured item made from a suitable rubber or plastics material.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows the body of the tension monitor in plan view with the top and O ring removed for clarity. The outside of the body is shown as being square but could be circular, rectangular or another shape to suit the application.

Figure 2 shows the complete tension monitor assembly in a cross sectional side view.

The top would probably be circular for ease of manufacture but could be any shape to suit the application. The tapped hole shown in the side of the tension monitor is for an air connection.

Figures 3 and 4 show examples of possible applications for the tension monitor.

t;iguie shows a possible pneumatic schematic circuit that could be used with the tension monitor.

Referring to Figure 2, under normal conditions the tension in the fastener passing through the tension monitor normally presses the top 2 hard against the body 1 and holds.the O ring 3 onto its seat. The O ring 3 thus prevents the loss of air from the body 1 of the tension monitor, the internal circular chamber of which is under pressure, supplied by the tapped hole shown. If the fastener works loose or fails completely, the O ring will lift off its seat and air will be released from the tension monitor. The loss of air will be detected by a pressure switch or other pressure sensitive device connected to it which could activate a suitable warning device, shut off power or initiate some other corrective action. The tension monitor is a fail- safe

device as spurious leakage of air from it would activate one of the possible systems described. Figure 3 shows a possible application where a load 5 is connected to one of its several supports 4 by a screw or bolt 6, washer 7 and nut 8. The other supports for load 5 are not shown but they would also be fitted with tension monitors. The tension monitor body l and top 2 (O ring 3 not shown) is fitted under the head of screw or bolt 6. Only one air connection 9 is shown but there could be two or more depending on the application. It should be noted that the tension monitor assembly (l, 2 & 3) could also be fitted under the nut 8. If the nut 8 works loose or the screw or bolt 6 fails completely, air would be released from the body l of the tension monitor and the loss of air would be detected by device such as a pressure switch or another pressure sensitive device which could either provide a warning or initiate a shut down of the system. Figure 4 shows another application for the tension monitor, this time on a tensioner.

The tensioner 13 is applying a force to a chain or cable 14. If the tension is lost for any reason air will be lost from the tension monitor with the same results as described above. Figure 5 show a simple pneumatic schematic for use with the tension monitor. Air is supplied from a reservoir 10 which then passes through a small choke I l via air connection 9 to the tension monitor assembly l, 2 & 3. The optimum size of the choke I l would have to be determined to both protect against excessive loss of air from the reservoir should the tension monitor operate, but also prevent over feeding and thus re-pressurisation of the tension monitor if only partial loss of tension is detected. In this example there are two air connections to the tension monitor and the other air connection goes to a pressure switch l 2. The pressure switch l 2 would be pressurised under normal conditions. Under fault conditions air would be lost from the tension monitor assembly l, 2, & 3, the pressure switch de-pressurised and a warning or other appropriate action instigated. This schematic only shows one tension monitor but as many as required could be connected together to protect various locations in the system.

Claims

1. A tension monitor that when fitted to any type of fastener, support or tensioning system will monitor and detect if the fastener, support or tensioning system works loose or fails completely.

2. A tension monitor as claimed in Claim 1 using a pneumatic system that when fitted

to a fastener, support or tensioning system will detect looseness or complete failure and will instigate an appropriate warning indication and/or shut down the system being protected.

3. The tension monitor works in conjunction with a pneumatic system that pressurises the monitor and detects loss of air from the monitor which in turn will instigate a suitable warning indication and/or shut down the system being protected.

4. A tension monitor as claimed in any proceeding claim which is made from metal, rubber or plastics material or from a combination of these materials.

5. A tension monitor substantially as herein described and illustrated in the accompanying drawings.